Horizontal continuous casting apparatus



1967 J. A. BLESSINGER ETAL 3,344,845

HORIZONTAL CONTINUOUS CASTING APPARATUS Filed Aug. 16, 1965 4 Sheets-Sheet 1 Oct 1967 J. A.'BLESSINGER ETAL 3,344,845

HORIZONTAL CONTINUOUS CASTING APPARATUS 4 Sheets-Sheet 2 Filed Aug. 16, 1965 A/sr J. A. BLESSINGER ETAL HORIZONTAL CONTINUOUS CASTING APPARATUS n 7 I I I I I I v I I I I I I I I I I I 1 I I I I I u 'III IIIIIIIIIIIIIIIIl'II/I/IIIII/l Oct. 3, 1967 Filed Aug. 16, 1965 s 2 a R K 5 m2 M m e r Pa .1 if 5 N5 m. M

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3, 1967 J. A. BLESSINGER ETAL 3,344,845

HORIZONTAL CONTINUOUS CASTING APPARATUS Filed Aug. 16, 1965 4 Sheets-Sheet 4 VIII/[1% I 222 ffi fam #3 ere/1520' c. Hazers.

BY MKM United States Patent 3,344,845 HORIZONTAL CONTINUOUS CASTING APPARATUS John A. Blessinger, Maryville, Tenn., and Gerald L. Molvik, East Wenatchee, and Richard C. Harris, Wenatchee, Wash., assignors to Aluminum Company of America, Pittsburgh, Pa., a corporation of Pennsylvania Filed Aug. 16, 1965, Ser. No. 480,055 2 Claims. (Cl. 164274) ABSTRACT OF THE DISCLOSURE Horizontal continuous casting of multiple metal ingots may pe effected wherein a plurality of molds are supplied by a single molten metal source and where the ingots are withdrawn by a common withdrawal and support means. Casting may be terminated at a selected mold by the insertion of a plug into an orifice across a branch trough at the mold entrance. Thereafter, casting may be restarted using a separate starting plug which is guided, preferably by a pair of rails, to maintain alignment with the mold. Independent drive means withdraw the starting plug at a rate independent of the common withdrawal means and starting plug response to the common withdrawal means is restricted. Support and withdrawal of the starting plug and the ingot connected thereto are transferred to the common withdrawal and support means after the separate starting plug has achieved the same withdrawal rate. The separate starting plug, alignment or guiding means therefor together with the independent withdrawal means are all positionable at any mold site.

This invention relates to a method and apparatus for continuous casting in horizontally disposed molds, wherein a plurality of molds share a common molten metal supply. Especially concerned is the casting of the light metals, aluminum, magnesium and their alloys.

In the continuous casting under consideration here a a common mold mounting plate to maintain their rigid position with respect to each other and the other equipment. Molten metal is supplied to a header trough and thence through branch troughs to each mold. The drastically chilled molds are generally separated from the molten metal by a partial barrier or closure made of a refractory or heat insulating material to prevent chilling of the molten metal before it reaches the mold walls. These partial closures, hereinafter designated the header plates, have openings to permit the passage of molten metal into the mold wherein'its progressive solidification begins so as to continuously form an ingot emerging horiz-ontally.

Some means is situated after the mold outlets to support the solidified ingots and to withdraw them from the molds. As the molds are aligned in a single horizontal plane and are in a general parallel relationship in this plane, the most practical method of supporting and withdrawing the ingots is by the provision of a series of rollers, or preferably a continuous belt, of suflicient width to support all the ingots.

While the mold is described as open ended, obviously the flow of molten metal out of the mold is closed. Once casting is underway such is accomplished by the solidified ingot. At the start of a casting run this is effected by a starting plug. In most cases there are a number of individual plugs, one per mold, mounted on a common frame. A casting run is initiated by positioning the starting plug assembly such that each mold is closed by a starting plug, introducing molten metal to each mold and plurality of horizontally disposed molds are mounted on a "ice withdrawing the starting plug assembly while drastically chilling each mold to progressively soldify an ingot emerging from each mold. After sufiicient ingot length is developed the starting plug assembly is removed.

This type of casting has proven highly successful in producing large quantities of ingot generally ranging from 4 to 9 inches in diameter which may provide stock for extrusion operations and the like. However, such a system has one serious hindrance. If one ingot starts to develop imperfections, such as excessive lap defects, surface tearing, liquation and the like, such generally cannot be alleviated without affecting the entire operation in that for repairing or replacing merely a single mold, or for instituting other corrective action for the affected mold, the entire casting line is generally shut down. This downtime creates additional problems in the molten metal feed and hold furnace systems as will be recognized by those skilled in the art. Another factor is the inevitable waste of metal and lost production associated with such interruptions. These factors and others make such shutdowns extremely costly. Thus the need arises for a system which permits the interruption of a defective casting operation at a single mold, repairing or adjusting the conditions causing the defect and thereafter restarting casting at this mold position, all without any interruption in the casting at the other mold positions.

Accordingly it is a primary object of this invention to provide for the continuous casting of a plurality of ingots in horizontally disposed open ended molds, whereby casting can be interrupted at any selected mold and thereafter re-instituted without any interruption to casting at any other mold.

Another object is to do so where the casting line includes a common molten metal supply and a common ingot support and withdrawal system.

Other objects will, in part, be obvious and will, in part, appear hereinafter in this description, including the claims appended hereto and the drawings in which:

FIGURE 1 is a plan, partly in cross-section, showing a multiple horizontal continuous casting apparatus in accordance with the invention;

FIGURE 2 is an elevation, partly in cross-section, of the FIGURE 1 casting apparatus taken along line II-'II in FIGURE 1, but including apparatus in accordance with invention;

FIGURE 3 is a fragmentary plan view, partly in crosssection, of a portion of the FIGURE 1 apparatus, taken at a higher elevation along line IIIIII in FIGURE 2 and showing additional features of the invention;

FIGURE 4 is an elevation, partly in cross-section, taken along line IVIV in FIGURE 2;

FIGURE 5 is an elevation, partly in cross-section, taken along line VV in FIGURE 3;

FIGURE 6 is an elevation, partly in cross-section, taken along line VI-VI in FIGURE 3;

FIGURE 7 is an elevation, partly in cross-section, taken. along line VII-VII in FIGURE 6.

Referring now to FIGURES 1 and 2, therein is shown a continuous casting apparatus 10 having four horizontally disposed molds 14, each rigidly mounted, by fastening means not shown, on a common mold mounting plate 16 so as to assure a fixed position with respect to the other molds and the other equipment. Each mold 14 is provided with some mold chilling means such as water channel 20 disposed around each mold and provided with a series of holes 22 to spray water 24 for chilling the ingot 30. In this manner both the mold and emerging ingot are chilled by water supplied to the moldby pipe feed means, or the like, not shown. Generally some means, not shown, is provided for lubricating the mold surface to ease passage of the ingot therethrough. The

3 molds are disposed in a single horizontal plane and are situated in parallel relationship to one another so that the ingots emerging therefrom are likewise in common plane parallel relationship.

Suitable means such as continuous belt 40 is provided to support and withdraw the solidified ingots emerging from the mold. A single continuous belt 40 of sufficient width to support all the ingots works quite dependably here and provides a single support and withdrawal means common to all the ingots. For purposes of this description this continuous belt is designated the prime mover, or prime ingot support and withdrawal means, and includes belt drums 42 and belt support plate 44 which, respectively, move and position the belt. The belt is aligned with the bottom surface of the mold to describe a prime mover pass line 41. The prime ingot support and withdrawal means is provided with some power means, not shown, such as a reversible variable speed electric drive. A suitable scheme for shearing or cutting the ingots to prescribed lengths can be situated at some location after the belt 40. Obviously some other prime ingot support and withdrawal means, such as rollers or the like may be employed, although the continuous belt has been found quite satisfactory. To complement the belt serving as the prime mover, one or more hold down rollers 46 are preferably disposed to bear against the upper surface of the emerging ingot, providing more positive traction or gripping between the belt and roller.

Another aspect of the hold down roller is that it serves to keep the ingots in axial alignment with the molds by preventing any ingot movement across the belt. The use of hold down rollers can be viewed as establishing a discrete zone of maximum influence for the prime ingot support and withdrawal means, i.e. the zone where the ingot is gripped between the belt and the hold down roller. Considering an ingot which has not yet reached this zone, some degree of movement by slipping along or across the belt may be encountered. However, once the ingot reaches this zone, such uncontrolled movement is substantially eliminated. When reference is made to prime ingot support and withdrawal means such is intended to include both combination and separate means although the former is preferred from the standpoint of simplicity.

On the molten metal side of the mold 14 is a main feed trough flowing into a distribution header 62 and thence through branch troughs 64 into each mold. The liquid level 61 is maintained at a higher elevation'than the ingot. The main feed distribution header and feed troughs all are lined with a refractory or heat insulating material 66 to prevent molten metal heat loss. The troughs, of course, are supported and reinforced by structural members such as backup plate 70 and posts 72, although such structural details are not fully developed herein in order to conserve space and more directly emphasize the inventive features of the development described herein.

At the entrance of each branch trough is situated a plate 68 adapted to be closed to the flow of molten metal as by a plug 76. In the embodiment shown, the tapered plug 76 is of graphite having a mean diameter of about 2 /2 inches and provided with a handle 78. The branch trough entrance plate 68 is provided with a tapered hole 63, of substantially matching size so as to be closed by the insertion of plug 76. In normal operation the plug 76, of course, is removed to permit passage of molten metal into the mold branch trough. At the entrance of each mold there is situated a header plate 18 having a hole 19 therethrough for the passage of molten metal from branch trough 64 into the mold. The header plate is made of a refractory or insulating material to avoid chilling the molten metal before it reaches the chilled mold. In the embodiment shown the header plate 18 is fitted into a matching opening in the mold mounting 4 plate 16 and held in position between the mold 14 and branch trough end member 15.

Each branch trough is provided with a drain hole 65 closed by a branch drain hole plug 67 which can be fashioned from a refractory paste material. Closing the branch entrance plate opening with plug 76 and removing the branch trough drain plug 67, as by driving it out the bottom, in the direction indicated by arrow 69, as with a hammer and a spike, permits stopping the flow of molten metal to the branch trough and draining of residual molten metal through the drain opening 65. This serves to effectively interrupt the casting at any individual selected mold without substantial danger to operating personnel and, further, without interrupting the casting at any of the other molds. The ingot is removed from the mold by the prime mover.

Once the casting is interrupted for a given mold, the mold may be replaced or repaired or other measures taken to alleviate the defective ingot production at that site. The next step is re-instituting or restarting the casting operation at the repaired mold, likewise without any casting interruption at the remaining molds. This is accomplished by use of a separate starting plug together with means for guiding and supporting such and for withdrawing such independently of the prime mover until the starting plug speed and ingot speed matches that of the prime mover, and placing the ingot on stream with the others to include the separate casting restart.

Referring to FIGURES 2 and 3 the separate starting plug 84 is positioned at the outlet of the mold 14 and rests upon guide rail assembly 86. As will be appreciated, the starting plug features some means, not shown, for connecting to the solidified ingot, steel wires, key arrangements, and the like, being known in the art for this purpose. The starting plug generally matches the mold opening in size and cross-section so that it can be inserted into the mold outlet to close such to the flow of molten metal at the start of a casting run and so as to fit between the prime mover belt and the hold down rollers.

The guide rail assembly 86 comprises a pair of guide rails 87 and some means of fixing the rails in rigid position with respect to the mold and the prime mover. It is noteworthy that the alignment here is highly critical to a successful casting start-up operation in that any misalignment can create ingot deflection problems, tearing, and the like, as will be appreciated by those skilled in the art. In the embodiment shown, the mold ends of the guide rails are rigidly connected to the mold mounting plate 16 by means of mounting ledges or abutments 88 having connecting pins 90 afiixed thereto. The front (mold) end of the rails is aflixed to the rail mounting frame assembly 92 comprising brackets 93 adapted by sleeve 94 aflixed thereto to mount on the connecting pins 90, and cross brace 96 to rigidly fix the brackets 93, and hence the guide rails 87, all with respect to one another. The rail assembly is thus movable from one mold position to another by placing the mounting sleeves 94 upon the connecting pins 90 situated at each mold site. The pins and the sleeves are advantageously constructed for a fairly snug fit to prevent any significant motion of the guide rails. Thus positioning the guide rail assembly mounting frame upon the connecting pins 90 assures a relatively fixed and stable rail configuration which is in proper alignment with the mold and the prime mover pass line 41. Proceeding to the rearward portion of the guide rail assembly and referring to FIGS. 2, 3 and 4, there is shown hold down lugs 98, one aflixed to each rail, connected by pin 100 to hold down yoke 102. A screw type jack is connected to a rigid member such as beam 112 which may be a portion of the support frame, not shown, for hold down roller 46. The jack, of course, is movably mounted to beam 112, as by means of a channel member 113 and set screw/114, such that it may be moved from one mold position to another. It is advantageous to provide some means, such as index markings, set screw indentations, or the like, to assure correct alignment of the jack with the mold axis. The jack is used to urge the rail hold down lugs 98, and hence the guide rails 87, against the prime mover belt 40 under a slight pressure to prevent any upward movement of the rails which might cause a slight vertical mis-alignment between the rails and belt.

The size and spacing for the rails 8-7 is something of a matter of choice in accommodating a specific range of ingot sizes. For instance a rail height and spacing of two and seven inches, respectively, accommodates an ingot size range of about 4 to 6 /2 inches diameter. The length of the rails is preferably such that the starting lug, and hence the ingot connected thereto, are guided and supported until the plug reaches the hold down roller. At this point, since the starting plug size substantially matches that of the ingot, it will be gripped between the prime withdrawal means, belt 40, and the hold down roller 46 which are spaced to grip the ingot. The starting plug '84 will then be under the sole influence of the prime withdrawal and support means and hence, further support by the rails is not necessary. It can thus be seen that ingot support and withdrawal can thus be conveniently transferred to the prime ingot support and withdrawal means.

Returning to the starting plug 84, it includes a pair of front guide lugs 118 and a rear guide lug assembly 120. Referring to FIGURES 2, 3 and 5 the front lugs include means for fastening to the starting plug 84, such as flange 122 and bolts 123. Each lug also features abutments 124 and 125 which bear against the top and inside surface of guide rail 87 to provide, respectively, vertical and horizontal support for the starting plug.

Referring to FIGURES 2, 3, 6 and 7, the starting plug rear guide assembly 120 includes a pair of guide lugs 130 having bearing surfaces 132 and 133 to bear against, respectively, the upper and outside surfaces of guide rail 87 to provide vertical and horizontal support for the rear portion of starting plug 84. The guide assembly 120 is afiixed to the starting plug 84 by means of bolts 134 and mounting lugs 136 affixed to the guide lugs 130. Also included is a tab 138 afiixed to the guide lugs 130 to facilitate connection to the independent starting plug withdrawal means described hereinafter. In the embodiment shown both alignment lugs 130, the withdrawal tab 138 and the mounting lugs 136 are formed as an integral structure as best shown in FIGURES 3 and 6.

In practicing the invention it is preferred that the starting plug be restrained from any responsiveness to the prime ingot withdrawal means, especially during the critical initial stages of the independent start-up operation. For instance, the rearward-most portion of the starting plug 84 is generally disposed to rest upon the prime moving belt 40 such as at point 140 in FIGURE 6 and possibly might otherwise be urged to move along with the belt 40. This restraint is conveniently accomplished by including in the starting plug rear guide assembly a pair of spring-opposed brake plugs 142 disposed to bear against the inner surface of the guide rail 87. In the embodiment shown the guide rail features a recess 144 for the brake plugs to ride in. One or more springs 146 can be disposed between the brake plugs to urge them outwardly against the guide rails with sufficient force to prevent any movement of the starting plug in response to the prime mover. A significant advantage of the embodiment shown in FIGURE 6 is that the rear guide lugs 130 and brake plugs 142 cooperate to maintain proper spacing of the guide rails 87. Another advantage here is that the interlocking of the brake plugs and the recess 144 provides additional vertical restraint especially as to any upward movement of the starting plug. This further assures close vertical alignment between the starting plug and the uninterrupted ingots.

Some provision is preferably made for compressing the springs 146 to relieve the force against the brake plugs 142 when placing the starting plug and rear guide assembly on the guide rails 87 This may be accomplished in the manner shown in FIGURE 6 wherein the brake plugs 142 are partially enclosed and retained by spring housings 148 which also partially enclose spring compressor plugs 150, a separate housing and spring being provided for each brake plug. As can best be seen in FIG. 6, rotating cam lever 152 ninety degrees in the clockwise direction causes an upward movement in the tie rod 154 connected to cam lever 152 by pin 153. The tie rod 154 connects at its bottom end to connecting lug 156 which in turn is pivotably mounted by pins 157 to spring compressor connecting rods 158 which have their other ends pivotably mounted by pins 159 to the spring compressor plugs 150. Upward movement of the tie rod 154, in response to cam lever 152 thus causes compression of the springs. Nut 160 on the tie rod 154 provides accurate adjustment of a spring force in the compressed position. The amount of braking force needed here is not very high in that the principal force to be overcome is that generated by friction between the starting plug and the prime ingot withdrawal belt 40. However, once the starting plug reaches the hold down roller 46 and is gripped between the belt and the roller the full prime moving force is exerted on the starting plug which should already have reached the prime withdrawal line speed. Thus the separately started ingot can be considered as returning to the casting line when it passes under the hold down roller.

The starting plug 84 is withdrawn from the mold 14 by means operating independently of the prime mover. Referring to FIGURES 2 and 7 variable speed electric motor 166 is mounted upon a rigid structural member 168 in a fashion which permits its movement across the ingots to be aligned at any ingot or mold position as by bracket member 169. As with structural member 112, beam 168 may be a portion of the support frame, not shown, for hold down roller 46. A flexible connecting cable, chain, or the like, 170 connects the variable speed motor 166 to the starting plug 84 by means of a pin 172 inserted through a loop or ring 174 at one end of the flexible connection and through the withdrawal tab 138 on the starting plug rear guide assembly. The configuration designated 178 represents a storage facility for the chain or cable 170 together with means coupling motor 166 thereto. Pulley or sprocket 176 is provided beneath the variable speed electric motor 166 to permit a bend of approximately in cable or chain 170 so that it can maintain a constant alignment with both the independent withdrawal means and the starting plug.

Of course, the independent drive means is of sufiicient power to overcome the motion restraining effect of brake plugs 142. Other variable power means may be used in lieu of the electric power means shown. For instance, a hydraulic drive means has been used successfully and those skilled in the art will undoubtedly derive other drive schemes.

One way of viewing the independent drive means illustrated is to consider such a variable speed power means connected by a flexible tension coupler, e.g. chain or cable 170, to the starting plug. The starting plug, in turn, includes brake means to keep the tension coupler rigid and prevent motion of the starting plug in response to the prime ingot support and withdrawal means, but permit motion in response to the independent withdrawal means.

' V In accordance with the invention casting is restarted by positioning starting plug guide rail assembly 86 upon the prime mover and the connecting pins 90, attaching hold down yoke 102 to the guide rail hold down lugs 98 and compressing jack so as to slightly urge the guide rails against the prime mover. The starting plug 84 is placed upon the guide rails 87 and inserted a short distance into the mold 14. As the rearward portion rests upon the prime mover the brake provisions of the starting plug rear guide assembly are actuated by rotating cam lever 152, in FIGURE 6, ninety degrees clockwise. At this point the independent drive chain or cable 170 is connected to the withdrawal tab 138 on the starting plug rear guide assembly 120, as shown in FIGURE 7, by means of pin 172 and the cable or chain slack is relieved by the action of the independent drive means 166 but without imparting any significant motion to the starting plug 84. Casting is restarted by withdrawing plug 76 from the opening 63 in the branch trough entrance plate 68. Of course, branch trough drain plug 67 is replaced previous to the restarting operation. As the molten metal passes from distribution header 62 into the branch trough 64, thereby filling the mold 14 with molten metal, the mold is chilled by means of causing water to flow through channel 20. The starting plug is immediately withdrawn at a gradually increasing withdrawal rate until it reaches the production speed of the other ingots, i.e. the withdrawal rate of the prime ingot support and withdrawal means. It is extremely important here that the initial starting plug movement be slow and controlled so as to avoid any spilling of unsolidified metal out of the mold outlet. By following the teaching of this invention the ingot withdrawal can be gradually brought up to production speed without such an occurrence. Once the ingot is up to production speed the withdrawal rate is held constant by independent withdrawal means 166 until the starting plug 84 has passed under hold down roller 46. At this point the starting plug and the ingot connected thereto are under the full influence of the prime ingot support and withdrawal means and the independent withdrawal means can therefore be stopped causing the chain or cable 170 to flex somewhat which facilitates convenient removal of pin 172 to free the starting plug 84 from the independent withdrawal means. The cable or chain 170 is then removed to its storage provision 178 on the independent withdrawal means. The sprocket or pulley 176 is elevated to allow clearance for the ingot by suitable means such as a telescoping arrangement whereby the bottom portion 182 of the sprocket support post telescopes into the upper portion 184 and is held in position there by set screw 186. The entire independent withdrawal means can then he slid out of position along structural member 168 if desired. The starting plug 84 is then freed from the ingot connected thereto and set aside as is the rail assembly 86, and the casting operation is resumed as before the interruption.

The invention has been described with particular reference to a preferred embodiment. However, many modifications to this preferred embodiment will suggest themselves to those skilled in the art and it is intended that the claims appended hereto include such other embodiments and practices as fall within the true spirit of the invention.

What is claimed is:

1. In continuous casting apparatus comprising a plurality of horizontally disposed open ended chilled molds sharing a common molten metal supply and common prime ingot support and withdrawal means, the improvement comprising means for closing the flow of molten metal to a selected mold without interrupting flow to the remaining molds and means for restarting casting at the selected mold comprising a separate starting plug constructed to close the mold outlet to the flow of molten metal,

8 means for supporting the starting plug so as to maintain said starting plug in axial alignment with said selected mold, means for withdrawing the starting plug and the-ingot connected thereto at a rate independent of the prime ingot withdrawal means,

means to prevent starting plug response to said prime ingot withdrawal means, and

means for transferring support and withdrawal of the starting plug and'the ingot connected thereto to the prime ingot withdrawal and support means.

2. In continuous casting apparatus comprising a plurality of horizontally disposed open ended molds sharing a common molten metal supply system having a distribution trough and branch troughs connecting such to each mold, and a common prime ingot withdrawal and support means, the improvement comprising means for closing the flow of molten metal to selected mold without interrupting flow to the remaining molds, said means comprising a partial barrier situated at the entrance of the branch trough, said partial barrier having a hole adapted to be closed by a plug and a plug for closing said hole, and

means for restarting casting at the selected mold comprising a separate starting plug constructed to close the mold outlet to the flow of molten metal,

means, positionable at any mold position, comprising a plurality of rails constructed and arranged to support the starting plug so as to maintain such in axial alignment with said selected mold, means affixed to said starting plug arranged to cooperate with said rails in guiding said starting plug,

independent drive means comprising a variablerspeed power means and a tension coupler connecting said power means to said starting plug,

means to restrict starting plug motion outwardly from said selected mold, said means being so constructed and arranged as to prevent starting plug response to the prime ingot support and withdrawal means but permitting response to said independent drive means, and

means for transferring support and Withdrawal of the starting plug and the ingot connected thereto to the prime ingot withdrawal and support means, said transfer means being arranged to take efiect after the starting plug and the ingot connected thereto have achieved the same withdrawal rate as the prime ingot withdrawal means.

References Cited UNITED STATES PATENTS 648,091 4/1900 Trotz 164-283 X 2,121,280 6/1938 Bell 164--262 2,401,491 6/ 1946 Lyons 164-252 2,565,959 8/1951 Frances 16489 X FOREIGN PATENTS 586,438 11/1959 Canada.

1,070,042 11/ 1958 France.

719,065 11/1954 Great Britain. 812,356 4/ 1959 Great Britain.

J. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner. 

1. IN CONTINUOUS CASTING APPARATUS COMPRISING A PLURALITY OF HORIZONTALLY DISPOSED OPEN ENDED CHILLED MOLDS SHARING A COMMON MOLTEN METAL SUPPLY AND COMMON PRIME INGOT SUPPORT AND WITHDRAWAL MEANS, THE IMPROVEMENT COMPRISING MEANS FOR CLOSING THE FLOW OF MOLTEN METAL TO A SELECTED MOLD WITHOUT INTERRUPTING FLOW TO THE REMAINING MOLDS AND MEANS FOR RESTARTING CASTING AT THE SELECTED MOLD COMPRISING A SEPARATE STARTING PLUG CONSTRUCTED TO CLOSE THE MOLD OUTLET TO THE FLOW OF MOLTEN METAL, MEANS FOR SUPPORTING THE STARTING PLUG SO AS TO MAINTAIN SAID STARTING PLUG IN AXIAL ALIGNMENT WITH SAID SELECTED MOLD, MEANS FOR WITHDRAWING THE STARTING PLUG AND THE INGOT CONNECTED THERETO AT A RATE INDEPENDENT OF THE PRIME INGOT WITHDRAWAL MEANS, MEANS TO PREVENT STARTING PLUG RESPONSE TO SAID PRIME INGOT WITHDRAWAL MEANS, AND MEANS FOR TRANSFERRING SUPPORT AND WITHDRAWAL OF THE STARTING PLUG AND THE INGOT CONNECTED THERETO TO THE PRIME INGOT WITHDRAWAL AND SUPPORT MEANS. 